Water soluble ethers of alpha cellulose



Patented Se t. 24,1940 2,216,045

UNITED sures PATENT OFFICE WATER sownm ETHERS or man onueureosa Donald H. Bowers, Mooreatown, N. J., and Louis H. Book and Alva L. Honk, Philadelphia, Pa., assihginorrs to Riihm & Haas Company, Philadelp a, a. i

No Drawing. Application May 21, 1937, Serial No. 145,042

3 Claims. (01. 260-231,

This invention relates to water-soluble methyl the application of heat. After the reaction is and ethyl ethers of a-CelllllOSe having a low decomplete the mixture is diluted with water and gree of alkylation. the quaternary ammonium hydroxide neutral- In application Serial No. 750,128 filed October ized. The ether can be precipitated by adding 5 26, 1934, now Patent No. 2,087,549 granted July a water miscible non-solvent such as ethyl alco- 5 20, 1937, of which this application is a continuahol, acetone,jetc. or by heating the aqueous solution-in-part, there is disclosed and claimed a tion to 85 C. It can be freed of quaternary new process of making ethers of 01-0811111088 ammonium salts by washing with hot water. which essentially consists in dissolving a-cellu- The methyl and ethyl ethers of a-cellulose havlose in an aqueous solution of a quaternary aming from 0.6 to 1.0 methoxy 'or ethoxy group 10 monium hydroxide and treating the solution with for each CeHmOs unit prepared by this method an etherifying agent. By that. process methyl are water-soluble compounds that differ substanand ethyl ethers of a-CBlllllOSB are obtained that tially from the known water-soluble methyl and are substantially different from those obtained ethyl cellulose ethers. They are more soluble in by prior art methods. water and produce solutions of higher viscosity 16 In the previous methods of making a-celluthan the known ethers. Because of the low delose ethers, it was necessary to introduce from gree of alkylation and absence of cellulose deg- 1.25 to 1.67 methoxy groups for each CsHioOs unit radation they possess more of the desirable in order to impart water-solubility to the methyl properties of a-cellulose. They form films of high 20 cellulose. It was not possible to obtain a watertensile strength that require no softening agent 20 soluble ethyl ether from undegraded cellulose. and because of the highviscosity of their aque- The water-soluble methyl ethers that contained ous solutions are; excellent thickening agents, fewer methoxy groups and all the water-soluble emulsifying agents, and dispersing agents. As ethyl ethers were obtained by first degrading the thickening agents they are useful in textile cellulose until it became soluble in alkali. printing pastes; in sizes or finishes for rayon, 5

By the process of the above mentioned parent cotton or paper; in rubber latex compositions application water-soluble methyl and ethyl and in other aqueous emulsions and suspensions. ethers of a-cellulose can be obtained that con- As emulsifying and dispersing agents they are tain from 0.6 to 1.0 methyl or ethyl groups for useful in preparing emulsions of resins, drying each CsHroOs unit without degradation of the 'oils, edible oils and fats, and polymeric organic 3 cellulose. Ethers of higher alkylation, those compounds such as polymerized acrylic, meththat contain more than 1.2 alkyl groups per acrylic and vinyl esters. They are valuable as C6Hl005 unit are not water-soluble. These difsticking agents in insecticide sprays and dusts ferences from the prior art, it is believed, are in which it is desirable to obtain cohesion to due to a more uniform distribution of the ether leaves and waxy surfaces. In insect sprays even 35 groups throughout the cellulose molecule brought when present in only minute quantities, they act about by the cellulose being in solution dur as spreading agents and give a uniform distribuing the etherification. In the prior art proction of spray particles over the surface being esses the cellulose is not in solution during reactreated. This property also makes them very 0 tion so that its exterior surface only is available useful in water vehicle paints. Films made'from 40 for reaction and the entering groups probably the ethers can be used in making medicinal capbecome concentrated at a few isolated spots. By sules and sausage casing. Their film forming the more uniform distribution of the ether properties also make them useful in permanent .groups the entire cellulose molecule is made to wave preparations. When applied to textiles or 5 partake of the properties of cellulose ethers, leather and subsequently calendered they impart whereby water-soluble cellulose derivatives are a high luster to the surface. When incorporated obtainable with the least possible modification in rubber they impart oil resistance and can be of the cellulose. used in oil resistant linings in rubber hoses or In preparing these new cellulose ethers a-CGI- containers. In many other ways their waterlulose is dissolved in an aqueous solution of a solubility, the high viscosity of the solutions, and 50 quaternary ammonium hydroxide preferably trithe tough films that they form make them valuamethyl benzyl ammonium hydroxide and treated ble industrial compounds. with a suitable methylating or ethylating agent a In the following examples representative such as methyl chloride, dimethyl sulfate, ethyl methods of preparation are given for purposes chloride and diethyl sulfate, preferably without of illustration. By varying the concentrations 5 degree modifications such as alkylation in stages and-the and'ratios of reactants ethers of lower or higher of alkylation can be obtained. Other preparation of mixed ethers while not illustrated will beapparent to those skilled in the art- Example 1.--A solution of cellulose is prepared by mixing 150 grams of bleached sulflte wood pulp with one liter of a 35% solution of trimethylbenzyl ammonium hydroxide in a steel dough mixer. After mixing one hour, 150 grams of dlethyl sulfate is slowly added, with constant agitation, over a period 01 one hour. The temperature rises slightly, but no-external heat is applied. After stirring for two hours, 1500 cc. of water is added and mixed in to form a clear, viscous solution. The solution may be neutralized with acetic acid without precipitating any of the ethyl cellulose. The solution, as prepared, is a good thickening agent. It may be dried into tough films. By precipitating with alcohol, a dry, resinous solid is obtained.

Analysis of Zeisel Method (J. Chem. Soc. 81, 318 and 115,193): 0.2787 gram of material gave 0.2189 gram of AgI. Percent. C2H5O=15.05. This corresponds to 0.6 ethoxy groups to one CsHioOs unit.

Example 2.A solution of cellulose is prepared by mixing 170 gr. of bleached sulfite cellulose with 700 cc. of a 40% solution of trimethylbenzyl ammonium hydroxide in a Werner-Pfieiderer type of mixer. After mixing one hour, 233 grams of diethyl sulfate is slowly added, with constant agitation, over a period of one hour. After mixing for five hours at room temperature, 2500 cc. of water is added slowly to form a clear, viscous solution. The solution is brought to neutrality with acetic acid, and heated to 85 C., whereupon the ethyl cellulose separates in curds, which are washed with hot Water. On cooling, these particles of ethyl cellulose redissolve to form a clear, viscous solution. The dry material analyzed as follows: 0.3082 gram of material gave 0.3545

gram of AgI. Percent. C2H50=22.0. This corresponds to 0.91 ethoxy groups to one CcHmOs unit.

Example 3.-A solution of cellulose prepared as in Example 1, is diluted with 130 cc. of water and 194 grams of diethyl sulfate is slowly added, with constant agitation, over a period of one hour. The material is then mixed at room temperature for six hours. It may be precipitated and "washed of AGI. Percent. Cal-1502201. This corresponds to 0.82 ethoxy groups to one CoHmOaunit.

Example 4.-A solution of cellulose is prepared by mixing 150 grams oi bleached sulflte wood pulp with 600 grams of a 35% solution of trimethylbenzylammonium hydroxide in a steel dough mixer equipped with a steam jacket. After mixing for one hour at room temperature, the roughy mass is warmed to 55 C. by runnin steam into the outerjacket of the mixer and as described in Example 1. Analuysis: 0.2969gram of; material gave 0.3116 -gram 1750 cc. oi! 4% aqueous sodium hydroxide is slowly added. The resulting solution is a syrupy liquid.

To 450 grams of cellulose solution prepared as above, is added slowly with constant agitation, grams of dimethyl sulfate. Some heat is evolved by the reaction and the mass is allowed to warm up to C. but no external heat is applied. After about two hours, the temperature falls to room temperature and stirring is continued for 18 hours. The reaction mass is poured into an equal volume of water in which it is almost completely soluble. The methyl cellulose may be isolated by neutralizing with acetic acid and adding one to two volumes of ethyl alcohol. The gelatinous precipitate is filtered and washed with alcohol. When dry it is a resinous solid soluble in water, but only slightly soluble in alcohol or acetone and insoluble in benzene or chloroform. In water it forms a viscous solution and may be used as a thickening agent. Analysis by Zeisel Method (J. Chem. Soc. 81, 318 and 115, 193):

0.2787 gram of material gave 0.2860 gram of AgI. Percent. CHaO=13.55. This corresponds to 0.72 methoxy groups to one C6H1005 unit.

We claim:

1. A water soluble ether of a-cellulose and an aliphatic monohydric alcohol containing less than 3 carbon atoms in which there are from 0.6 to 1.0 alkoxy groups to each Cal-11005 unit.

2. A water soluble ethyl ether of a-cellulose in which there are from 0.6 to 1.0 ethoxy groups to each Cal-11005 unit.

3. A water soluble methyl ether of a-CBHUIOSG in which there are from 0.6 to 1.0 methoxy groups to each Cal-11005 unit.

DONALD H. POWERS. LOUIS H. BOCK. ALVA L. HOUK. 

